Oil field operators dedicate significant resources to improve the recovery of hydrocarbons from reservoirs while reducing recovery costs. To achieve these goals, reservoir engineers both monitor the current state of the reservoir and attempt to predict future behavior given a set of current and/or postulated conditions. Reservoir monitoring, sometimes referred to as reservoir surveillance, involves the regular collection and monitoring of measured production data from within and around the wells of a reservoir. Such data may be collected using sensors embedded behind the well casing and/or from measurement devices introduced into the well within or in line with the production tubing. The data may include, but is not limited to, water saturation, water and oil cuts, fluid pressure and fluid flow rates, and is generally collected at a fixed, regular interval (e.g., once per minute) and monitored in real-time by field personnel. As the data is collected, it is generally archived into a database.
In addition to monitoring conditions within the well, the equipment used to extract product from the well is also monitored. Such monitoring ensures that the equipment is functioning as close to its optimal operating point as possible or practical, and that failures are detected and resolved promptly. One type of equipment used downhole to extract product from oil and gas wells is an electric submersible pump (ESP). ESPs are generally mounted in line with the production tubing where they are submerged within the product present within the well when the tubing is lowered into the well's production casing. ESPs both pump the product to the surface and lower the flowing bottom hole pressure (FBHP). The decrease in FBHP increases the pressure differential between the formation and the well and accelerates the movement of product from the formation into the well through perforations in the casing.
Power to drive an ESP is provided from the surface via cables that also provide conductors for signals to be received from the ESP at the surface. Data transmitted to the surface may include, but is not limited to, motor temperature, motor drive current frequency, pump intake pressure and pump discharge pressure. Although the data provided enables monitoring of the performance of an ESP, determining the underlying cause of a failure or a variation in the performance of an ESP is a more complicated task. A given ESP failure or performance variation can have numerous causes and operators strive to identify the cause of such conditions quickly to reduce any resulting downtime or reduced production. While experienced reservoir personnel may rely on their personal experience to diagnose and resolve such conditions, a more automated approach based on a broader information base offers the possibility of diagnosing conditions and providing more optimal solutions in a shorter period of time.
It should be understood that the drawings and corresponding detailed description do not limit the disclosure, but on the contrary, they provide the foundation for understanding all modifications, equivalents, and alternatives falling within the scope of the appended claims.